Ignition Table help for Toyota Straight 6

[Dozer2FEYota]

Hey Folks,
I have had some pinging that kinda' surprised me based on what all my reading and the initial timing calc spit out, and wondering if anyone has a similar engine tuned that they could share.

NA, hoping to have a 87 and a 93 tune by the time it's all said and done.
Toyota "2FE" -> 2F block and 3FE head and induction.
Calculated compression is around 9.1 -9.2:1
Cylinder bore is 95mm
2 valves / cylinder
combustion chambers look like this:

3fe combustion chamber.jpg

Here is my ignition table. I'm seeing pinging at high VE, more at higher RPM.

Yes, I know I need to dial that down and that's the plan, but just wanted to see if anyone has a comparable engine and compare contrast.

Ignition Table.jpg

Thanks in advance.

[Drew442]

Hey Folks,
I have had some pinging that kinda' surprised me based on what all my reading and the initial timing calc spit out, and wondering if anyone has a similar engine tuned that they could share.

NA, hoping to have a 87 and a 93 tune by the time it's all said and done.
Toyota "2FE" -> 2F block and 3FE head and induction.
Calculated compression is around 9.1 -9.2:1
Cylinder bore is 95mm
2 valves / cylinder
combustion chambers look like this:

3fe combustion chamber.jpg

Here is my ignition table. I'm seeing pinging at high VE, more at higher RPM.

Yes, I know I need to dial that down and that's the plan, but just wanted to see if anyone has a comparable engine and compare contrast.

Ignition Table.jpg

Thanks in advance.

Here's my Ford inline 6 map. It's read upside down to the mega squirt, idle is top left.

It's a sohc 4 litre cross flow. The chambers are more open than yours, compression is the same.

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[Dozer2FEYota]

Thanks Drew. Not sure that a SOHC would be apples and oranges to my little pushrod tractor motor, but I really appreciate the data point! Cheers!

[Drew442]

Thanks Drew. Not sure that a SOHC would be apples and oranges to my little pushrod tractor motor, but I really appreciate the data point! Cheers!

Oh, I thought that motor was sohc...

Here's the 'same' Ford motor but with the earlier push rod head.

The combustion chambers look even more like yours on this motor. I think the compression ratio was about 9:1

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[slow_hemi6]

If that is a 9:1 chamber then the slugs have to be down the hole a bit at tdc or you have a thick head gasket or both.
Drew is that last map for a crossie? I had programmable ignition on my old crossie years ago and they respond well to a bit of extra timming.

[Dozer2FEYota]

That's awesome Drew. I assume this is tuned for 87? That's not a lot of advance, but I think that's exactly where I'm headed to get rid of my pinging. I was fully expecting to be high 30's all in on this engine. The other thing that surprises me is the advance at idle you have there... I initially tried tuning at 22 myself, as the recommendation of the guy who "tuned" this for me on dyno, but I couldn't get it smooth. OE uses 7 at idle, but most bump it to around 10. I finally found that 12 is far more stable for my truck.

I will say that people that run this combo (2F block w/ 3FE head) using the stock ECU say that if you cut the head or block much, it will rattle.

Thanks so much Drew, I think you have confirmed that what I am seeing is not out in left field.

[Dozer2FEYota]

If that is a 9:1 chamber then the slugs have to be down the hole a bit at tdc or you have a thick head gasket or both.
Drew is that last map for a crossie? I had programmable ignition on my old crossie years ago and they respond well to a bit of extra timming.

Some of this is plagiarized from a user on IH8MUD.COM, but it applies to my engine as well:

I calculated a "squish" volume of just under 93cc for a stock 3FE based on a compression ratio of 8.1:1 and a swept volume of 659.2cc.

i.e.
(swept volume + squish volume) / squish volume = 8.1

(659.2cc + x) / x = 8.1
x=92.8cc


Since the chamber measured ~77cc, that leaves ~16cc that is accounted for by the head gasket thickness and any space between the deck "plane" and the piston.

If you sub in the swept volume of the 2F (705.1cc) you get a "stock 2FE" compression ratio of:
(705.1cc + 92.8cc) / 92.8cc = 8.6:1

Since my engine is bored 1mm over and the head shaved .030, I calculate around 9.1 - 9.2

[slow_hemi6]

You should always measure your own engine.
Given what you have quoted there is 16cc, made up of, the area the piston is down the bore at tdc and the gasket area. At your bore area that is about 2.271mm or 89.5 thou drop.
Average head gasket is about 45 thou at crush so your piston should be 44.5 thou down if it is a flat top. Dish is going to see the edges a bit higher in the bore.
The chamber in the photo with zero decked flat tops would be an easy 10:1

[Dozer2FEYota]

You should always measure your own engine.
Given what you have quoted there is 16cc, made up of, the area the piston is down the bore at tdc and the gasket area. At your bore area that is about 2.271mm or 89.5 thou drop.
Average head gasket is about 45 thou at crush so your piston should be 44.5 thou down if it is a flat top. Dish is going to see the edges a bit higher in the bore.

If and when I pull the head next, I'll be a bit more careful and cc the chambers, measure deck clearances, etc. This is the first engine build, and it was pure stock outside of mosh-mashing Toyota vintages and a bit of (necessary) machine work. At the time, I hurried more than I should have and skipped some stuff like this since it was a "basic" build, but I'm learning that "woulda' shoulda' coulda' " is a mutha.

By the way, how can I measure compressed HG thickness? Only OE and FelPro are available aftermarket. Nobody makes a "nice" MLS or similar with that spec advertised.

Thanks for the input!

[slow_hemi6]

When you have a used one that has been compressed, then you can measure the thickness of the fire ring. I always use the same type of felpro's on mine. Hold up good to my 11:1.
I used to be a nut for 277ci hemi 6cyl engines. I used to build them about 10:1. Those engines taught me that big timing numbers are not needed and are detrimental if the engine has a very quick burn. The WOT curve on mine maxed out at about 26-28 degrees as I recall. Yet my small block want's 34.

[Drew442]

Yeah it's a crossie.

I totally forgot about fuel on this motor. I believe your 87 number is MON scale? We use RON in Australia.

I forgot that crossie was LPG which is around 100 RON. The first post I did for the SOHC is 98 RON.

I don't know the conversion...

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[slow_hemi6]

87 over there is like our 91 unleaded. I only ever ran my 88 crossie on 91(87). Totally stock except for the ignition. As I said it surprised me how much timing it liked, don't remember it ever being prone to pinging.